Summary of Work: Diet may play a role in immune function, particularly Diet may play a role in immune function, particularly with respect to autoimmunity. Dietary interventions (e.g., antioxidant supplementation, manipulation of the fat content) can prolong survival in murine models of systemic lupus erythematosus (SLE). The role of these dietary factors in the etiology of SLE in humans has not been examined. The objective of this study is to examine the influence of diet on the risk of SLE. We are using data from the Nurses= Health Study, a cohort of 121,000 women ages 30-55 followed with biennial questionnaire assessment since 1976. Food frequency and nutritional supplement data were collected from 93,184 members of this cohort in 1980. Data on SLE occurrence were collected in 1982, 1984, 1986, and 1992. Two rheumatologists independently reviewed medical records; 57 SLE cases diagnosed after the 1980 diet assessment have been verified, and the 1992 through 1996 potential cases are currently being reviewed. We calculated incidence rates and rate ratios from 1980-1990 for each quintile of energy-adjusted nutrient intake. In the preliminary analysis of 57 cases, SLE incidence SLE incidence decreased somewhat with higher intakes of Vitamin C and E: rate ratios (RR) and 95% confidence intervals comparing the highest to the lowest quintiles of intake (including supplements) were 0.52 (0.21-1.3) for vitamin C and 0.52 (0.22-1.2) for vitamin E, and tests for trend were p=0.20 and 0.36, respectively. This was not seen when we excluded supplement users: for vitamin C, RR=1.1 (0.42-2.8) and for vitamin E, RR=0.89 (0.36-2.2). There was little evidence for an association with vitamin A or total fat intake. Future analyses will use updated nutrient data from the 1984 and 1986 assessments and will include additional food specific analyse.